U.S. Pat. No. 4,526,822 discloses shaped articles prepared from copolyesters of terephthalic acid, trans-4,4'-stilbenedicarboxylic acid, and ethylene glycol having improved gas.barrier properties and U.S. Pat. No. 4,468,510 discloses copolyesters of 2,6-naphthalenedicarboxylic acid, terephthalic acid, trans-4,4'-stilbenedicarboxylic acid, 1,2-propanediol, and 1,3-propanediol having improved gas barrier properties. Blends of these polymers with other polymers are not disclosed in either patent.
Japanese Kokai 72348/74 discloses specific blends of 40 to 45 weight % of the homopolyester of trans-4,4'-stilbenedicarboxylic acid and 1,6-hexanediol with the polyester prepared from dimethyl terephthalate and 1,4-butanediol (PBT). These blends have enhanced heat resistance compared to unmodified PBT. No poly(ethylene terephthalate) blends are disclosed.
U.S. Pat. Nos.2,657,194 and 2,657,195 broadly or generally disclose polyesters of various stilbenedicarboxylic acid isomers with oxyalkylene glycols having 2 to 6 oxyalkylene linkages, as well as certain other glycols, aminoalcohols, and diamines. Various glycols are disclosed containing 2 to 16 carbon atoms but blends of these polymers with other polyesters or other polymers are not disclosed (see column 8, line 36 of U.S. Pat. No. 2,657,195). U.S. Pat. No. 3,496,839 relates to low molecular weight homopolymers of 4,4'-stilbenedicarboxylic acid and aliphatic glycols useful in radiation-cured crosslinked polyester coatings. Our own U.S. Pat. Nos. 4,420,607, 4,459,402, 4,468,510, and 4,526,822, all disclose polyesters based on trans-4,4'-stilbenedicarboxylic acid using various glycols. No examples or teachings of blends are given.
Other patents which disclose trans-4,4'-stilbenedicarboxylic acid polyesters are U.S. Pat. Nos. 2,657,194, 3,190,774, 3,247,043, 3,842,040, 3,842,041, and 4,073,777. Polyesters of trans-4,4'-stilbenedicarboxylic acid and neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, and 1,10-decanediol are disclosed by Meurisse, et al., in the British Polymer Journal, Volume 13, 1981, page 57 (Table 1). Jackson and Morris disclose homopolyesters from trans-4,4'-stilbenedicarboxylic acid and various aliphatic glycols in the Journal of Applied Polymer Science, Applied Polymer Symposia, 41, 307-326 (1985).
Heretofore, blends of poly(ethylene terephthalate) and copolyesters from trans-4,4'-stilbenedicarboxylic acid and aliphatic glycols have been unknown.